The present invention relates to a recording and reproducing apparatus for use in an optical disk apparatus or the like.
Optical disks are being used as image recording devices for image information filing. Image information in the form of documents is photoelectrically converted by two-dimensional light scanning, and the image information thus converted is recorded by an image recording device or retrieved and reproduced as hard or soft copies as the occasion demands.
With this kind of optical disk apparatus, the optical disk conventionally has data recorded in a spiral track or in concentric circular tracks, and data is recorded on or reproduced from the optical disk by means of an optical head which is moved linearly in the radial direction of the optical disk by the linear motor.
The spiral or concentric circular tracks on the optical disk are sectioned for each unit of data which has a certain length, such as a block, and a block address data which is previously recorded at the foremost end of the block.
The data on the disc is digital-coded, and that data which corresponds to one block is recorded continuously starting from the block data address. When data which is only a previously determined code is recorded continuously from the block address, however, discrimination of the block address data becomes difficult and thus provides a problem of recording and reproducing the data accurately.
In order to solve this problem, the rotary encoder, servo-disk and the like which rotate together with the optical disk are molded as the means for discriminating the header of the data on the optical disk. Even when these means are employed, however, sufficient accuracy is difficult to obtain when data is recorded at high density.